Induction of mucosal antibodies by live attenuated and inactivated influenza virus vaccines in the chronically ill elderly.

Induction of local antibody responses to influenza A virus hemagglutinin by coadministration of two vaccines was investigated. Fifty elderly nursing home residents received inactivated trivalent influenza virus vaccine intramuscularly and simultaneously were randomized to receive either bivalent live attenuated influenza A virus vaccine or saline placebo intranasally in a blinded fashion. More significant increases in anti-H1 and -H3 IgA antibodies were detectable in nasal wash specimens of subjects who received live attenuated virus vaccine than in those who received intranasal placebo. The increased anti-hemagglutinin IgA antibody response was of longer duration in recipients of live attenuated vaccine. The change in antibody titers after vaccination was positively correlated with total blood lymphocyte counts measured before vaccination in both vaccinee groups (P < .05). There was a possible advantage of administering live attenuated with inactivated virus vaccines because of enhanced local antibody responses.